Climate impacts on water resources
The main climate change consequences related to water resources are increases in temperature, shifts in precipitation patterns and snow cover, and a likely increase in the frequency of flooding and droughts.
Depending on the region, climate change will have widely differing effects on Europe’s water. Higher temperatures will generally intensify the global hydrological cycle. Annual precipitation trends in Europe indicate that northern Europe has become 10%-40 % wetter over the last century, whereas southern Europe has become up to 20 % drier. Over the last century annual river discharge has increased in some regions, such as eastern Europe, while it has fallen in others, such as southern Europe.
Climate change may also markedly change the seasonal variation in river-flow. Higher temperatures will push the snow limit upwards in northern Europe and in mountainous regions. This, in conjunction with less precipitation falling as snow, will result in a higher winter run-off in northern European and mountain-fed rivers, such as the Rhine, the Rhône, the Po, and the Danube. Moreover, earlier spring melts will lead to a shift in peak flow levels. As a result of the declining snow reservoir and decreasing glaciers, there will be less water to compensate for the low flow rates in summer.
Climate change tends to increase the frequency and intensity of rainfall; there may be an increase in the occurrence of flooding due to heavy rainfall events. Groundwater recharge may also be affected with a reduction in the availability of groundwater for drinking water in some regions.
Changes in average water availability in most European river basins are estimated to be relatively small for the next 30 years. However, in the long-term most climate change scenarios predict that northern and eastern Europe will see an increase in annual average river flow and water availability. In contrast, average run-off in southern European rivers is projected to decrease. In particular, some river basins in the Mediterranean region, which already face water stress, may see marked decreases of water availability.
Changes in Europe’s water resource will have consequences for several economic sectors. Low water and droughts have severe consequences on most sectors, particularly agriculture, forestry, energy, and drinking water provision. Activities that depend on high water abstraction and use, such as irrigated agriculture, hydropower generation and use of cooling water, will be affected by changed flow regimes and reduced annual water availability. Moreover, wetlands and aquatic ecosystems will be threatened. This will affect the sectors that depend on the goods and services they provide.
Climate change and European water policies
The integration of climate change into European policies such as the Water Framework Directive (Directive 2000/60/EC) has not taken place yet. The directive itself does not include specific provisions to address climate change impacts. However, upon request from EU Member States, an extensive assessment of the potential impacts of climate change on water resources was carried out in 2005 (Eisenreich, 2005). In February 2007, a symposium organised by the EU German Presidency discussed climate change and the European water dimension. In October 2005, the European Commission launched the second phase of the European Climate Change Programme focusing on impacts and adaptation. To support this process the EEA has compiled a summary of best practices in Member States in adapting to climate change in the water sector (EEA, 2007). This will be followed by a Green Paper from the Commission in 2007.
Climate change is also part of the Directive on Flood Risk Management; it is one of the key issues to consider when Member States undertake an initial assessment of the flood risks and draw up the risk management plans. Similarly, climate change has to be taken into account in relation to water management planning regarding droughts and water scarcity.